# !/usr/bin/env python3
# -*- coding: utf-8 -*-
import os
from flask import Flask


# create_app 函数是一个约定俗成的函数名, 不可以更改
def create_app(test_config=None):
    app = Flask(__name__, instance_relative_config=True)
    # instance_relative_config: 告诉 flask 配置文件是相对于 instance folder
    app.config.from_mapping(
        SECRET_KEY='dev',
        # 在实际生产中应该设为任意值
        DATABASE=os.path.join(app.instance_path, 'flaskr.sqlite'),
        # app.instance_path 是 Flask 选择的 instance folder
    )
    if test_config is None:
        # load the instance config, if it exists, when not testing
        app.config.from_pyfile('config.py', silent=True)
    else:
        # load the test config if passed in
        app.config.from_mapping(test_config)

    # ensure the instance folder exists
    try:
        os.makedirs(app.instance_path)
    except OSError:
        pass

    # a simple page that says hello
    # @app.route('/hello')
    # def hello():
    #     return "Hello, World!"

    from . import db
    db.init_app(app)

    from . import auth
    app.register_blueprint(auth.bp)

    from . import blog
    app.register_blueprint(blog.bp)
    app.add_url_rule('/', endpoint='index')

    return app
